In general, a smart key system is a system in which when a driver of a vehicle with a smart key take a necessary action, a vehicle embedded system senses the action to control operations of the vehicle, and includes a Remote Keyless Entry (RKE) system and a Passive Keyless Entry (PKE) system. The RKE system is a system that can lock or unlock a door wirelessly and remotely without a key, and the PKE system is a system in which a driver or owner of a vehicle positioned near the vehicle wirelessly executes operations of locking, unlocking, and starting of the vehicle. Here the smart key may be typically referred to as a “Fob key,” and shortly referred to as a “Fob.” The smart key system of the vehicle includes multiple LF antennas for covering, as a communication region, a vehicle outdoor region in addition to a vehicle indoor region, a RF antenna for receiving an RF signal from a smart key, and an SMK unit. The SMK unit in the smart key system transmits an LF signal through an LF antenna to detect a fob in the vicinity of the vehicle. When the LF signal is received, the smart key transmits an RF signal as a response signal, and the SMK unit determines whether the RF signal received through the RF antenna is matched with a previously stored vehicle identification number. If the RF signal is matched with the vehicle identification number, the SMK unit performs a function of driver/assist/trunk passive access depending on circumstances.
However, in the smart key system, if the smart key information is just matched with the vehicle identification number, the vehicle may be controlled irrespective of who a user is. Thus even when through a stranger manipulates a smart key because of theft or loss, the vehicle control may be allowed such as locking/unlocking of a door, locking/unlocking of a trunk, and starting of a vehicle.